Sensitized photographic emulsion



SENSIIZED -PHOTOGRAVPHIC EMULSION Filed Dec. 8, 1939 Goo 50o 4.00

l l l 600 500 l 400 verziors,

tion, examples describing the preparation -of sensivtizers according to the invention.

Patented Aug.. 5, 1941 UNi'rED STATES .PATENT v(31st-ii;

sENsrnzEn rno'roGnArn'lo EnfluLsioN Frits Bauer, Dessau, and Gustav Wllmanns, Wolfen, Kreis Bitterfeld, Germany, assignors, by mesne assignments, to General Anilino Film Corporation, New York, N. Y., a' corporation of Delaware Application December 8, 1939, Serial No. 308,148'

In Germany Dece mber 9, 1938 -z claims'. (ci. eas-'ii Recently there have been published carbocyanine dyestuifs and especially trimethinecyanines containing an oxdiazole, thiodiazoleor selenodiazole ring. substituted by the methyl group. Such dyestuffs containing the methylthiodiazole ring have been described for photographic sensitizing. The methyloxdiazolecarbocyanines are supposed to also sensitize photographic emulsions, but until now no-delinite dyestuff with information about its sensitiaing qualities has been described. f

According to this invention we have found that trimethine dyestuils containing the furyloxdiazole ring show very favourable sensitizing qualities and aby far. higher sensitizing intensity than the known methyloxdiazolecarbocyanines.

This furyloxdiazole ring is placed von the one side of the trimethine chain, whereas' to the other side may be attached any of the heterocyclic nitrogenous rings known in cyanine dyestuif chemstry. v

These dyestuifs are capable of sensitizing any silver halide emulsion, but preferably are applied for sensitizing silver chloride emulsions, their spectral sensitivity being only so much enlarged, that theycan still be worked in bright yellow or green dark-room light. A special advantage of the new dyestu's is their ability to be rapidlyI and't'horoughly washed out from the light sensitive emulsions.

The ydyestuffs are prepared according to the w-aldehyde condensation process by `condensing with the quaternary salt of the 2-methyl-5-furyloxdiazole in presence of pyridineand acetic anyhdride, the u-aldehydes of the' heterocyclic nitrogenous nuclei which are commonly used in cyanine dye'stuff chemistry and which are selectedfrom the group consisting of thiazole, oxazole,

20` anol.

40 mum 460 ma.

l drawing.

Example 1 1 A dyestuif of the following constitution has'a sensitizing maximum at about 488 mi.

'rms dyestun 1s prepared in the following way; 3.2 g'. N-ethyl-2-methine-thiaaoline-u-aldehyde .lo are dissolved in l0 cc'. pyridine and'l20 drops acetic anhydride. With stirring and cooling in '.o freezing mixture 5.9 g. 2mothy1sfury1ox diazole 'methiodide are added in portions. After 5 stirring for about one hour in the cold, l0 cc. methanol are added and treated with 30 cc. 10% sodium perchlorate solution. After adding some pieces of ice the dyestuf! crystallizes. yis sucked ofi' and recrystallized several times from meth- Absorption maximum 460 mp. v- When incorporated in a silver hloride emulsion the dyestuif has a sensitivity curve corresponding to thatillustrated in Figure 2 of the accompanying drawing.

Examplez vA dyestul! of the following constitution has a sensitizing maximum at about 488 mi.

This dyestuil is prepared in the'following' way: 2.5 g. N methyl 2 methine -thiazoline u alde- '5 hyde are .dissolved in 10 cc. pyridine and '120 drops aceticanhydride. While cooling with. a freezing mixture and stirring -5 g.- 2-methyl5 furyl-oxdiazole-m'ethiodide are added. Further treatment as in Example 1. -Absorption maxi- When in` 'rporated in a silver chloride emulsion the dyestuff shows a sensitivity curve corresponding to Figure 3 of theaccompanying Examplev 3 1 Avdyestuff of the following constitution has a sensitizlng maximum at about 480 pa.

'rms dyostuu is prepared in the following way: 3.2 g. N-ethyl-2-methine-thiazoline-u-aldehyde. 55 are dissolved in 10 Zec. pyridine and 120l drops ceac anhydride@ .By cooling m a freezing v ture and stirring 6.2 g.' v2methyl5-furyi-oxas in Example 1. Absorption maximum about 460 um. l When incorporated in a silverchloride emulsion the dyestui! shows a sensitivity curve cor,

responding to Figure 4 ot the accompanying drawing.

We claim: 4 f

1. Photographic ysilver halide gelatin emul'- sions containing e 'Iuryloxdiazoie-trimethinecyi anine dyestutl.

2. Photographic silver halide gelatin emulsions containing a furyloxdiazole-trimethinecyanine dyestuf! selected'from the group consisting of a. furyloxdiazole furyloxdiazole -trimethinecyanine dyestuif, a furyloxdiazole-thia-trimethinecyanine dyestulf; a furyloxdiazole-oxa-trlmethinecyanine dyestui'f. a turyloxdiazole-indotrimethinecyanine dyestuii'; a furyloxdiazole-quino-trimethinecyanine dyestui! ando.' furyloxdiazole-thiaz'oline- 10- trimethinecyanine dyestufl. I

i FRITZ BAUER. i GUSTAV WILNIANNS. 

